Worcester Air Quality in 2025
In 2025, Worcester's air quality (Worcester, MA-CT area) had a median daily AQI of 39 (Good) across 365 monitored days. 1 day (0.3%) reached Unhealthy for Sensitive Groups or worse, 296 were Good, and the year's peak AQI was 108 (Unhealthy for Sensitive Groups). Ground-level ozone set the daily AQI on 276 of those days. The cleanest month of 2025 was October (median AQI 30, 0 days above 100) and the worst was August (median 44, 1 day above 100, peak 108).
- Good: 81.1%
- Moderate: 18.6%
- Unhealthy for Sensitive Groups: 0.3%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Worcester
Today's main pollutant in Worcester is ground-level ozone (AQI 32). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How was Worcester's air quality in 2025?
Good on a typical day: median AQI 39, with 1 day above AQI 100 out of 365 monitored — the 3rd cleanest of 7 years on record for the area.
- ✓Peak AQI in 2025: 108 (Unhealthy for Sensitive Groups).
- ✓Ground-level ozone was the main pollutant on 276 days.
- ✓Cleanest month: October; worst: August.
Frequently asked questions
What was the average AQI in Worcester in 2025?▾
EPA's Air Quality System puts Worcester's (Worcester, MA-CT) median daily AQI for 2025 at 39, which is Good. 1 day were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 108.
Which month had the worst air quality in Worcester in 2025?▾
The cleanest month of 2025 was October (median AQI 30, 0 days above 100) and the worst was August (median 44, 1 day above 100, peak 108).
Was 2025 a good or bad year for Worcester's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 3rd cleanest by days above AQI 100. 2025's median of 39 is below the area's typical annual median of 43.
Worcester month by month in 2025
Worcester air quality month by month, 2025 (Worcester, MA-CT, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 39 | 0 | 73 | O3 |
| February | 28 | 40 | 0 | 56 | O3 |
| March | 31 | 43 | 0 | 52 | O3 |
| April | 30 | 45 | 0 | 87 | O3 |
| May | 31 | 36 | 0 | 61 | O3 |
| June | 30 | 47 | 0 | 100 | O3 |
| July | 31 | 44 | 0 | 91 | O3 |
| Augustworst | 31 | 44 | 1 | 108 | O3 |
| September | 30 | 36 | 0 | 49 | O3 |
| Octobercleanest | 31 | 30 | 0 | 71 | O3 |
| November | 30 | 31 | 0 | 59 | O3 |
| December | 31 | 34 | 0 | 55 | O3 |
How 2025 compares
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 3rd cleanest by days above AQI 100.
2025's median of 39 is below the area's typical annual median of 43.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Worcester
The latest EPA AirNow observation puts Worcester's AQI at 32 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Worcester air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Worcester, MA-CT), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.